Construction method of variable curvature annular stiffening core cast-in-place concrete beam

The invention relates to a construction method of a variable curvature annular stiffening core cast-in-place concrete beam. The construction method is characterized by comprising the steps of controlling the positions of a bottom formwork and side formworks through a bottom support, longitudinal supporting bodies, a slant steel body, lateral displacement adjusting bodies and longitudinal displacement adjusting bodies; limiting the positions of a steel reinforcement cage and a stiffening core steel tube through reinforcing steel bar protective layer thickness adjusting bodies and stiffening core position adjusting bodies respectively; after concrete is poured to reach the thickness of a protective layer, placing reinforcing steel bar supporting steel discs into reinforcing steel bar supporting steel disc connecting grooves in the bottom formwork through reinforcing steel bar position adjusting rods; after concrete is poured to reach the bottom face of the stiffening core steel tube, placing stiffening core limiting plates into stiffening core limiting plate connecting grooves in the bottom formwork or the side formworks through stiffening core position adjusting rods; after concrete pouring in the formworks is completed, pouring concrete into the stiffening core steel tube. By means of the construction method, accurate positioning of the cast-in-place concrete beam and the stiffening core space can be achieved, the thickness of the midspan reinforcing steel bar protective layer can be controlled dynamically, and concrete pouring quality can be improved.